Christmas or festive lights are typically organized as a string of sockets and cooperating lights, which lights are electrically connected in a series configuration. Therefore, when one lamp is faulty, the entire string fails to light. It is necessary therefore to locate the one faulty lamp and replace it. If there is more than one faulty lamp, it is necessary to locate multiple lamps. Typically, this requires extracting each lamp and inserting a known good lamp therefor. For a string having upward of fifty lamps, this can be time consuming.